The present invention relates to an ignition system for a gas turbine engine, and more particularly to an ignition system which delivers a first single high-energy spark followed by subsequent sparks of lower energy.
Gas turbine engine ignition systems typically include an ignition exciter that generates the discharge energy used to fire the ignition plugs or igniters. These circuits are commonly used within the aviation industry, but are not limited to aircraft turbine engines. For example, gas turbine generators and other small turbine engines will typically utilize exciter circuits to provide spark energy to one or more igniter plugs.
A start sequence for a gas turbine engine that coordinates engine speed, ignition and fuel delivery to achieve a reliable start. Conventionally, a dedicated starter motor or a starter-generator, is drivably coupled to the gas turbine engine and is operated to produce rotation thereof. As the starter accelerates the engine, a fuel delivery pump driven by a gearbox attached to a rotor of the gas turbine engine provides fuel flow thereto. The igniters are then fired to effect ignition in a combustor of the engine. Upon successful ignition, and once the engine has reached a self-sustaining speed, the starter is disengaged.
In operation of gas turbine engines, specifically Auxiliary Power Units (APUs), failure to start may result due to ice build-up on the ignition plug tip. Such occurrences may be of particular concern during high altitude operation.
Accordingly, it is desirable to provide an ignition system for a gas turbine engine that ensures start reliability by specifically clearing ice build-up at the ignition plugs in an inexpensive, uncomplicated and lightweight arrangement.